1. Field of the Invention
This application relates to well tools and more particularly to test tools which are run on a flexible line and are operated by tensioning and relaxing the same for opening the well for flow and for shutting it in at a downhole location, in order to gather well test data.
2. Description of the Prior Art
It has been common practice to shut in a producing well near its producing zone, thus to reduce the storage volume below the shut-in point so that pressure therein could approach stabilization with that of the producing formation much more quickly than could occur were the whole well bore pressurized. Likewise, when the well is re-opened to flow, the pressure in the well below the shut-in point reaches a point of stabilization more quickly. Well test data are commonly gathered both during build-up periods and draw-down periods.
Some tests require that the well be tested by a series of shut-in and flow periods during which test data are gathered.
Injectivity testing is commonly carried out in the case of injection wells. For such tests, injection of fluids into the reservoir is stabilized and the well is shut-in near the formation. The fall-off or reduction of pressure below the shut-in point is recorded, and after the fall-off has stabilized, the well may be opened up for another injection period. If desired, pressures may be observed and recorded during both the injection and the shut-in periods. The tests may involve any number of injection and shut-in periods.
Subsequent to such tests, the data gathered are analyzed to determine various characteristics of the reservoir.
Test tools for carrying out well tests have generally been run on a flexible line, that is, a wire line ("slick line") or an electrical cable. Many of the test tools either include a valve or are associated with a valve and are so related that the test tool, after being anchored in a receptacle, is used to operate the valve between open and closed position by tensioning and relaxing the slick line or electrical cable. Other tools may operate in the opposite manner, being actuated to the open position in response to tensioning the flexible line. Usually, the test tool is lowered into the well, its lower end portion anchored in a receptacle, and the flexible line then tensioned to close the valve and thus shut-in the well, and the flexibile line is afterwards relaxed to open the valve and allow the well to flow. If an electrical cable is used, the tool string will usually include sensor means for sensing pressure below the valve and sending appropriate electrical signals to the surface for readout and/or display and storage. Of course an electronic memory gage can be used, but in such case the memory cannot be unloaded until the test tool is withdrawn from the well.
A slick line can be used to run a test tool and a battery-powered memory gage into a well. And a slick line can also be used to run a test tool into the well with a mechanical recording gage. In this case, the chart made by the gage is read after the test tool is withdrawn from the well.
The relaxing of the flexible line does not pose a problem, since when the line tension is reduced sufficiently, the movable portion of the test tool moves down, but it is readily understandable that tensioning of the flexible line will pose a considerable problem if such tests are to be carried out on offshore wells, for instance.
The problem arises due to the fact that the offshore well is anchored in the earth and therefore stands still in the water while the surface craft supporting the flexible line reel rises and falls in response to the waves on the surface of the water and may also be buffeted by the wind. Under such circumstances, it is at best extremely difficult to hold proper tension on a test tool to maintain it in the up mode, whether that be the test tool's open or closed position.
It is desirable to have the ability to slack the flexible line not only when the test tool is in its "down mode" but also when it is in its "up mode" so that the motion of the surface craft due to wave action will not affect operation of the test tool in the well. Thus, much time and money can be saved by eliminating erroneous and/or incomplete surveys.
Further, it is desirable to provide a test tool of the nature discussed above, but which is ideally suited for carrying out tests in wells, especially offshore wells, since the nature of the tool permits the flexible line to be slacked as much as desired whether the tool is open or closed.
Applicant is familiar with the following prior patents which relate to the subject matter which relates to the present invention. These prior patents are:
______________________________________ Re.31,313 3,664,427 4,051,897 4,134,452 4,149,593 4,159,643 4,274,485 4,278,130 4,286,661 4,373,583 4,420,044 4,487,261 4,583,592 4,625,799 4,669,537 4,678,035 ______________________________________
Applicant is familiar also with a brochure published by Flopetrol-Johnston covering their MUST Universal DST device, and with an editorial comment published in WORLD OIL magazine, page 21, October 1983 Edition.
In addition, Applicant is familiar with U. S. Pat. Nos. 4,051,897 issued to George F. Kingelin on Oct. 4, 1977; 4,134,452 issued to George F. Kingelin on Jan. 16, 1979; 4,149,593 issued to Imre I. Gazda, et al. on Apr. 17, 1979; 4,159,643 issued to Fred E. Watkins on July 3, 1979; 4,286,661 issued on Sept. 1, 1981 to Imre I. Gazda; 4,373,583 issued Feb. 15, 1983 to Fleming A. Waters; U.S. Pat. No. Re. 31,313 issued July 19, 1983 to John V. Fredd and Phillip S. Sizer, on reissue of their original U.S. Pat. No. 4,274,485 which issued on June 23, 1981; and U.S. Pat. No. 4,278,130 issued July 14, 1981 to Robert T. Evans, et al, all of which disclose test tools which may be run on a wire line or cable and used to open and close as well at a downhole location by pulling up or slacking off on the wire line or cable by which these test tools are lowered into the well. In each of the above cases, a receptacle device is first run on a wire line and anchored in a landing nipple, then a probe-like device is run and latched into the receptacle.
U. S. Pat. No. 4,051,897 issued to George F. Kingelin on Oct. 4, 1977 and discloses an early type of well test tool for running on a flexible line and anchoring and sealing in a receptacle located downhole in a well whereby the well can be controlled at such downhole location by tensioning and relaxing the flexible line to open the well to flow and to shut it in to stop flow so that well pressures could be determined below the test tool both during the flow period and during the shut-in period. The problem with this test tool was that its flow capacity was very small (too small for suitable flow tests and was used for equalizing pressures across the tool so that it could be safely removed from its anchored position). The present invention is an improvement over the device of U.S. Pat. No. 4,051,897.
U.S. Pat. No. 4,134,452 provides only a tiny flow passage therethrough openable and closable by tensioning and relaxing the conductor cable for equalizing pressures across the tool.
U.S. Pat. No. 4,149,593 is an improvement over the device of U.S. Pat. No. 4,134,452 and provides a much greater flow capacity as well as a locking sub which locks the tool in the receptacle with a tenacity somewhat proportional to the differential pressure acting thereacross.
U.S. Pat. No. 4,286,661 is a divison of U. S. Pat. No. 4,149,593, just discussed, and discloses an equalizing valve for equalizing pressures across the device disclosed in U.S. Pat. No. 4,149,593.
U.S. Pat. No. 4,159,643 discloses a device similar to those mentioned above and has a relatively small flow capacity. This tool has lateral inlet ports which are closed by tensioning the conductor cable.
U.S. Pat. No. 4,373,583 discloses a test tool similar to those just discussed. It carries a self-contained recording pressure gage suspended from its lower end and therefore sends no well data to the surface during the testing of a well. This tool, therefore, may be run on a conventional wire line rather than a conductor line, since it requires no electrical energy for its operation.
U.S. Pat. No. Re. 31,313 discloses a device similar to that of U.S. Pat. No. 4,373,583 in that it has lateral inlet ports which are opened and closed by moving a probe up or down through tensioning or relaxing the wire line or cable on which it is lowered into the well.
U.S. Pat. No. 4,487,261 issued to Imre I. Gazda on Dec. 11, 1984 and discloses a well test tool which is an improvement over the well test tool of U.S. Pat. Nos. 4,051,897; 4,134,452; 4,149,593; and 4,286,661. This improved test tool has a much increased flow capacity made possible by placing the landing receptacle in the well tubing string as a portion thereof but could only be retrieved by retrieving the tubing.
U.S. Pat. No. 4,583,592 issued to Imre I. Gazda and Phillip S. Sizer on Apr. 22, 1986. This test tool is similar to the test tool of U.S. Pat. No. 4,487,261 but lands in a landing receptacle which forms a movable part of a bypass assembly. Tensioning the flexible line not only closes the test tool but also closes the bypass passages of the bypass assembly. The test tool releases from its anchored position after a predetermined number of open/close cycles. The flow capacity can easily be as large as the flow capacity of the tubing with which it is used.
U.S. Pat. No. 4,669,537 issued to William D. Rumbaugh on June 2, 1987 and discloses a well test tool utilizing a lock device having a sliding sleeve valve thereon, the lock device for anchoring and sealing in a landing nipple downhole. The running tool used to install the test tool is also used to open and close the sleeve valve. Any number of cycles may be had. On the last cycle the sleeve valve is left closed as the running tool is separated therefrom. A pulling tool is then run to equalize pressures across the test tool and to then unlock and retrieve it from the well.
U.S. Pat. No. 4,678,035 which issued to Pierre Goldschild on July 7, 1987, together with the MUST brochure and the WORLD OIL article, disclose the drill stem test tool having a non-retrievable valve opened and closed from the surface by tensioning and relaxing the conductor cable connected to the probe-like tool latched into the valve. Even with the valve open and the well producing, no flow takes place through the probe. All flow moves outward through the side of the valve into a bypass passage which then empties back into the tubing at a location near but somewhat below the upper end of the probe. The probe automatically releases when a predetermined number (up to twelve) of open-close cycles have been performed.
U.S. Pat. No. 3,664,427 which issued to Thomas M. Deaton on May 23, 1972 and U.S. Pat. No. 4,420,044 which issued to William H. Pullin on Dec. 13, 1983 show tools which utilize a type of zig-zag slot and pin arrangement for controlling relative longitudinal movement between two relatively slidable parts and providing alternate long and short strokes. U. S. Pat. No. 4,625,799 which issued to William H. McCormick and Charles C. Cobb on Dec. 2, 1986 shows use of a continuous zig-zag slot to cause relative rotational movement in response to relative longitudinal movement between two relatively slidable parts.
All of the U. S. patents listed and discussed above are incorporated herein by reference thereto for all purposes.
There is not found in the prior art known to Applicant a test tool for opening-up a well and shutting-in a well at a downhole location by tensioning and relaxing the flexible line by which such test tool is lowered into the well, wherein such test tool can be caused to remain in its upper position while the flexible line is slacked off as would be convenient to do to allow for movement of a surface craft relative to an offshore well.